Casing mill



Oct. 20, 1942. R. E. coNNER 2,299,528

CAS ING MILL Jaffa/away.

R. E.. CONNER CAS ING MILL Oct. 20, 1942.

Filed Sept. 22, 1941 2 Sheets-Sheet 2 INVENTOR. da; f3. GM

.or force upon the cuttingmembers lWeight to the cutters.

Patented Oct. 20, 1942 UNITED 'STA'I'Ei CASING MILL Ray E. Conner, Houston, TeX.

Application September 22, 1941, Serial No. 411:825

Y10 Claims.

'The `invention relates to a easing mill, and particularly t0 a mill to be used in a well bore for milling pipe or casing.

In many instances in well drilling and produc ing operatic-ns it is desirable to out a string of pipe either by severing it into two pieces so that one portion may be removed, or in other inN stances it is desirable to entirely remove ,a section of the pipe for carrying on desirable operations at that elevation .in the well where the pipe has been removed.

In operating milling tools fin a Well bore considerable diiliculty has been encountered in applying a predetermined or proper amount of Weight to accomplish the cutting action. it will be appreciated that a 'long string of pipe suspended in a well bore is subject to considerable stretch and it is dilicult to know at the surface exactly lhow much weight is being applied to the cutters. The string of operating pipe Ahas considerable weight vand it is only necessary to apply a small Vportion of this I-f 4an excess of weight vor force is, applied, the cutters may be lbroken or damaged or be caused to cut rinto the pipe being severed by cutting too great an amount.

It is also one of the objects of the present -invention to provide a milling cutter wherein only a predetermined force is applied to the cutters and `wherein any excess is then taken by additional roller or supporting members carried by the operating pipe. In this manner only a predetermined force is applied to the cutters and damage or injury is avoided.

Another object of the invention is to provide a casing mill with a retractible head so that a predetermined force can be provided which will to force the cutters against the Worn.

Another object of the invention is to provide a casing mill with. a housing and sliding cutter head so that the housing contact the cutting facing and absorb all but a predetermined portion of the load applied `through the operating pipe.

Still another object of the invention is to provide alternate cutters and rollers in a casing mill so as to roughen the `working face to permit the cutters to obtain a greater bite.

Still another object of the invention is to provide an actuating mechanism ior the cutters of casing mill so that a signal will be given to surface by a variation in hydraulic pressure to indicate when the cutters are extended.

Another object of the invention is to provide a to Figs. l and 2, res

casing mill with extensible cutters and supporting rollers.

Other and further objects the invention will be readily apparent when the following descriptionis considered in conv ecton with the accompanying drawings wherein:

Fig. 1 is a vertical sectional View through the tool ready to be lowered into the Well vbore with the section taken on the lline of the cutters.

Fig. 2 isa View similar to Fig. 1, but with ,the section taken at ,right anglesI to the lsection of Fig. 1.

Figs. 3 and 4 are sections takenon the lines 3 3 and @-5 rc-:spectivi-zly of Fig. l.

Figs. 5 ,and S are sectional Yviews corresponding ect lJ, but illustra-ting the tool las lpr-ing extended and in operating position.

Fig. 'l' is section taken on the line l-'l of Fig. 5.

The tool of the present invention is to be lowered into the well bore l: of an operating string 0f pipe .2 which may ce any length in order to lower tool to `the ed eleva v in itl-.e well here. This pipe carries a housing '3, which is hollow `arrafiged to telescopically receive a cutter head1-5.

The cutter head l has a stern thereon which extends into the housing rFhis has a shoulder' 6 carrying athrust l wh. .h is en gaged by the lower end of a coil spring il. The

upper end of this Spring engages a thrust ring `tataloly in the housing.

This cutter head has a of cutter members I4 pivoted on the shafts in the lower end thereof. Thesecutte. workin he recesses l@ so that they are extensie` in position shown Yin vFig. 5.

Inorder to actuate the cutters lui-,a plunger t8 is slidably arrangedi-nside or the headand stem and is normally urged upwardly by a .sp-ring i9 engaging against a `plate 2Q in the head. This plunger carries a flange lw h engages the heel portion of each of Ithe c tters 'to urge the kcutters to retracted position, as in Fig. -1. An upper flange 24 is also carried by the plunger i3 and -is arranged to engage the upper surface 25 of the heels 22 so as to move the cutters` to extended positions when the plunger moves downwardly, as seen in'Fig. 5.

.In order to .actuate this plunger apstn 39 is attached to the upper end thereof and is arranged to move in a working barrel 3l, which is attached to the upper end of the stem 5. A suitable packing 32 prevents leakage of fluid past the working barrel.

It seems obvious that when hydraulic pressure is applied through the operating pipe 2, that such pressure will engage the piston 3U and cause it to move downwardly to the position shown in Fig. 5, where such plunger has moved into an enlarged portion 33 in the working barrel so as to permit the by-passing of some of the uid.

When the piston moves to the position of Fig. there will be a reduction in the resistance to the ilow of iiuid so that there will be a drop in pressure at the surface and the operator will thus receive an indication that his cuttersrhave been extended.

The toe portion 35 of each of the cutters constitutes a cutting edge so that as they are pivoted outwardly from the position of Fig. l to the position of Fig. 5, they will Contact the inside surface of the pipe 36 which is to be cut. In this way the hydraulic pressure can be used to force the cutters outwardly to penetrate the pipe and make the initial cut. During this initial cutting operation the operating pipe 2 will be rotated to rotate the cutter head, but the pipe will be held at a constant elevation until such time as the piston 30 moves into the opening 33 to signal the operator that his cutters are fully extended.

Where it is desired to cut awayany considerable length of the pipe 3S so as to leave an open portion in the well bore, or for any other reason, it is desirable to more than just sever the pipe it is necessary to apply considerable weight to the cutters in order to accomplish the cutting action. Overloading of the cutters however may break the cutters, and with this in mind a special construction has been arranged upon the housing 3.

It seems obvious that the spring 8 may be of a desired strength such as to apply the desired pressure to the cutters and the cutter head upon the face 31 which is being cut on the upper end of the pipe 35, as seen in Fig. 5. Thus, when the cutters I4 have been extended, the operating pipe 2 will be lowered somewhat so as to compress the spring 8, and in this manner apply a load to the cutters. The exact elevation of the cutting tool in the well is not known at the surface because of the stretch of the string of pipe hanging in the well, and therefore the exact amount of lowering which will apply the desired load upon the cutters can hardly be estimated from the surface. The torque applied to a string of pipe may also change its length as the long operating pipe winds up several turns or revolutions when a pipe is being cut.

With a view, therefore, of arranging a construction so that the operator can predetermine the amount of load to be applied to the cutters and to avoid overloading the cutters. the lower end of the housing 3 has been equipped with a set of rollers or supports 4I). These supports are in the form of arms 4I pivoted at 42 and carrying the roller members 43, as best seen in Fig. 2. `These supporting arms are normally retracted, as seen in Fig. 2, so that the tool may be lowered into position. After the cutters have been extended, as seen in Fig. 5, then the operating pipe is lowered to compress the spring 8, and as this pipe moves downwardly, the supporting rollers will engage the inclined face 44 on the cutter head so that these supporting arms will be pivoted outwardly to the position shown in Fig. 6. In this position the shank portions 45 of the support arms engage the face 46 on the housing to limit the outward movement of the support arms. As will be seen in Fig. 6, the rollers 43 now rest upon the face 3l being cut by the cutters I4.

The only force applied to the cutter head and the cutters is therefore the force of the spring 8 which is now compressed. Any additional weight or force due to the lowering of the operating pipe 2, will be taken by the rollers riding on the face S'I. In this manner only a predetermined load can be applied to the cutters and any injury or damage to the cutters will be avoided.

It will be noted that the rollers 43 are toothed or roughened at 4I so that they will bite into the surface 37 and roughen the surface, as seen at 48 in Fig. '7, just ahead of the cutters I4. This will permit the cutters to take a greater bite and speed up the cutting action.

When suicient cutting has been accomplished,

y it is only necessary to lift up on the operating pipe 2 and to out off the ow of hydraulic pressure, whereby the cutters will be retracted by the plate ZI and returned to the position of Fig. 1, and the supporting arms will return to the position of Fig. 2.

Broadly, the invention contemplates a casing mill wherein a predetermined load is arranged to the cutters, and wherein a signal is rendered to the operator to indicate that his cutters are extended.

What is claimed is:

1. A casing milling tool to penetrate and cut away a section of pipe or casing in a well bore comprising a housing, a set of roller mills thereon, a cutter head carried by said housing, cutter members on said head, a plunger carried by said ead and operable by hydraulic pressure to extend said cutters, said roller mills being adapted to support said tool by engaging a surface formed by said cutters and a telescoping connection between said housing and head with means therebetween so that only a predetermined force is applied to said cutters.

2. A casing milling tool to penetrate and cut away a section of pipe or casing in a well bore comprising a housing, a set of roller mills thereon, a cutter head carried by said housing, cutter members on said head, a plunger carried by said head and operable by hydraulic pressure to extend said cutters, said roller mills being adapted to support said tool by engaging a surface formed by said cutters and a telescoping connection between said housing and head with means therebetween so that only a predetermined force is applied to said cutters and any excess of force is carried by said rolling mills.

3. A casing mill including a set of cutters, a set of rollers to contact the surface being cut, an operating pipe connected to said rollers so that the load of the pipe is carried by said rollers, and resilient means to transmit a predetermined force to said cutters.

4. A casing mill including an operating pipe, a set of cutters carried thereby, spring means to transmit a predetermined force from the pipe to the cutters. and roller members to also Contact the surface being cut to absorb any additional force so as to protect said cutters.

5. A casing mill including an operating pipe, a set of cutters carried thereby, spring means to transmit a predetermined force from the pipe to the cutters, and roller members to also contact the surface being cut to absorb any additional force so as to protect said cutters, said rollers being toothed so as to roughen the surface being cut to permit a greater bite by the cutters.

6. A mill for pipe in Wells including a housing, a cutter head normally extended therefrom, cutters on said head, a plunger movable in said head by hydraulic pressure to actuate said cutters, and roller supports on said mill to roll`on the portion of the pipe being cut to support the load of the tool.

7. A mill for pipe in Wells including a housing, a cutter head normally extended therefrom, cutters on said head, a plunger movable in said head by hydraulic pressure to actuate said cutters including means to vary the hydraulic pressure when said cutters are extended, and roller l5 cutters on said head, a plunger movable in said 20 head by hydraulic pressure to actuate said cutters including means to vary the hydraulic pressure when said cutters are extended, and roller means on said housing to roll on the pipe being cut to prevent more than a predetermined load on said cutters.

9. A mill for pipe in Wells including a housing, a cutter head normally extended therefrom, cutters on said head, a plunger movable in said head by hydraulic pressure to actuate said cutters including means to vary the hydraulic pressure when said cutters are extended, and means on said housing to prevent more than a predetermined load on said cutters including resilient means and roller members to Contact the face being cut.

10. A mill for pipe in Wells including a housing, a cutter head normally extended therefrom, cut ters on said head, a plunger movable in said head by hydraulic pressure to actuate said cutters to rst penetrate the pipe and to retract the cutters upon reduction of the hydraulic pressure, means to support the mill on the pipe being cut, and additional means to resiliently advance said cutters against the pipe.

RAY E. CONNER. 

